Orphaned blocks are not disabled when placed with a single click

Create a function with one parameter. If you just click once on the parameter name, this is interpreted as grabbing the block and dropping it immediately. There seems to be a race condition or some other weird behavior here: sometimes the dropped block is disabled, but other times, it's not - leading to a top-level "x" expression in the program. Dragging that block anywhere does cause it to become disabled.